Add a full screen virtual keyboard to virtual keyboard root window

ui/keyboard/keyboard_util.h

Index: ui/keyboard/keyboard_util.h
diff --git a/ui/keyboard/keyboard_util.h b/ui/keyboard/keyboard_util.h
index 8769825f679e8f0872b439f8364e0b152d0c17d9..29ed0a8f10f9b014baf4234ecb37cd1b78ea9f89 100644
--- a/ui/keyboard/keyboard_util.h
+++ b/ui/keyboard/keyboard_util.h
@@ -35,6 +35,9 @@ enum KeyboardControlEvent {
 // Returns true if the virtual keyboard is enabled.
 KEYBOARD_EXPORT bool IsKeyboardEnabled();
 
+// Returns true if the keyboard usability test is enabled.
+KEYBOARD_EXPORT bool IsKeyboardUsabilityTestEnabled();
+
 // Insert |text| into the active TextInputClient associated with |root_window|,
 // if there is one. Returns true if |text| was successfully inserted. Note
 // that this may convert |text| into ui::KeyEvents for injection in some